1. Technical Field
The present invention relates to bicycle chains, and more particularly to a chain plate structure featuring that when the chain plate structures are assembled as a chain having plural chain elements, two spaces are formed in each said chain element, thereby contributing to steady and fast shifting operation with reduced noise.
2. Description of Related Art
FIG. 15 depicts an example of a conventional chain for bicycle transmission. Therein, a chain (A) routes around a derailleur's guide pulley (B) and a transmission sprocket (C), for allowing transmission and shifting operation. While the chain (A) has its each two aligned chain plates (A1) spaced by a fixed interval, the chain-engaging teeth (B1) of the guide pulley (B) and the chain-engaging teeth (C1) of the transmission sprocket (C) are different in thickness. As a result, it is impossible for the chain-engaging teeth (B1) of the guide pulley (B) and the chain-engaging teeth (C1) of the transmission sprocket (C) to be both fittingly received in the interval between the two aligned chain plates (A1) of the chain (A). Instead, at least one of the two kinds of teeth (B1) (C1) only gets too loose or too tight engagement with the chain (A), and this can adversely affect the efficiency of transmission and shifting operation.
As an attempt to address this problem, Taiwan Patent No. M400969 published on Apr. 1, 2011 and titled “PLATE BODY FOR INNER PLATE AND INNER PLATE HAVING THE SAME” discloses a plate body, wherein the plate body is used for a bicycle chain, which has two of the plate bodies assembled face to face, and serves as an inner plate of the bicycle chain. The plate body comprises a pair of through holes and a raised portion that is defined between the two through holes and faces the other plate body. Therein, the raised portion is equidistant from the centers of the two through holes. Thereby, the chain can be maintained tilted during shifting operation, so as to improve the holding force of the chain exerting on the chain pulley.
However, in the prior patent, the interval between the raised portions of the two aligned chain plates is still fixed, so the problem that at least one of the two kinds of teeth only gets too loose or too tight engagement with the chain remains unsolved and the poor efficiency of transmission and shifting operation persists.